1. Field of the Invention
The invention relates to a frequency converter for an immersion vibrator.
2. Description of the Related Art
Immersion vibrators are used for compressing concrete while it is still liquid. To do this, a vibrator bottle which is part of the immersion vibrator is immersed in the concrete, and an electric motor and an imbalance, which is driven by this electric motor at a high rotation speed, are accommodated in this vibration bottle. In order to achieve the required motor rotation speed and hence compression frequency, the motor must be supplied with a special voltage, whose frequency (for example, 200 Hz) is greater than the mains frequency provided by the public mains system.
It is known for the special voltage to be provided by a special voltage network or by a frequency converter, which is either provided on site in the form of a large stationary unit, or is an integrated component of the immersion vibrator. An immersion vibrator with an integrated frequency converter is known from DE G 92 17 854.5.
CH689598 A5 describes an immersion vibrator in which a converter can be disconnected from a protective sleeve which is fitted with a vibration bottle. The protective sleeve is coupled to the converter via a specially designed electromechanical plug and socket structure, so that not only is it possible to transfer the special voltage, but this also ensures a mechanically firm connection between the protective sleeve and the converter housing. The specific configuration of the electromechanical coupling means that the elements to be coupled must be accurately matched to one another. It is impossible to use components which are not equipped for the specific coupling.
Immersion vibrators with an integrated frequency converter have proven to be excellent in practice. However, as before, immersion vibrators which do not have their own frequency converter and must be fed by an external frequency converter are still used on building sites. These immersion vibrators are primarily distinguished by their cheaper procurement costs. However, on building sites, they require either an appropriate special voltage network at a low voltage level and a high voltage frequency, or a conventional frequency converter, which must be provided where the work is being carried out in the form of a very heavy box. This makes it very difficult to operate such an immersion vibrator.